State Sen. Steve Hobbs is hiking solo on what seems an impossible mission.

The Lake Stevens Democrat is trying to stitch together political support for a 10-year, $10 billion transportation package financed primarily with a carbon fee and a gas-tax increase.

Hobbs, who is chairman of the Senate Transportation Committee, calculates a sum of that magnitude would pay for removing state-owned culverts to improve fish passages, redoing the U.S. 2 trestle and building five electric-powered ferries. It also would pay Washington’s share of a new I-5 bridge across the Columbia River, construct a new interchange on Highway 522 at Paradise Lake Road and fulfill items on the wish lists of lawmakers across the state.

“This addresses major transportation needs. This addresses a lot of environmental challenges, and we get a carbon policy,” he said.

Hobbs knows the odds of him succeeding are slim. It took three years of sometimes-bitter negotiations to complete the $16 billion transportation package enacted in 2015. Here he is attempting to produce a less expensive but no less complicated version in less than six months.

Yet the centrist Democrat, who’s been targeted by about every political force and even his own party over the course of his career, is embracing a quixotic legislative route so Washington can build highways, save salmon, reduce air pollution and price carbon all at once.

The effort, he said, “is fraught with political minefields, and the only one who is going to be hurt if one explodes is me. But I’m going to charge ahead.”

He started in earnest in late November, meeting separately in Seattle with some of the muscle of the state’s business, environmental and labor communities, and federally recognized tribes. In those conversations, Hobbs began mapping avenues of potential agreement and disagreement.

As now imagined, the plan is to rely on a fee of $15 per metric ton of carbon emissions and a 6-cent increase in the gas tax to cover the bulk of the costs.

Other components include a doubling of the annual fee paid by owners of electric vehicles; increases in the sales tax levied on auto parts, bicycles and rental cars; and a new statewide transportation impact fee on homes, commercial buildings and manufacturing plants.

Of the $10 billion, $3.1 billion would go to remove state-owned culverts as required by a U.S. Supreme Court directive. An additional $200 million would be available for dealing with local culverts.

Along with almost $5 billion for roughly a dozen highway projects, Hobbs has penciled in money for maintenance of existing highways and construction of five new state ferries. There are line items for cities and counties, transit districts, freight mobility improvements and grants for bicycle and pedestrian safety projects.

How the carbon fee would be handled is one example of an initial point of contention. Last month voters rejected an initiative to set a $15 fee that would rise over time. The money raised would have been spent on energy-saving, climate-assisting endeavors as determined by a public board.

Hobbs’ plan is to lock in the fee at $15, a notion businesses prefer and environmentalists don’t. And he steers carbon fees into the state transportation budget to be spent removing culverts, building ferries and carrying out projects sought by lawmakers. Had the initiative taken the same approach, it might have had a better chance of being approved, he said.

Rep. Jake Fey, D-Tacoma, the incoming chairman of the House Transportation Committee, is aware of Hobbs’ effort but is not involved in advancing it. “I’m not discouraging him to work on it,” Fey said. “We’ll certainly be paying attention to what the Senate comes out with.”

If it comes out with anything.

“It’s a pretty delicate balancing act.” Hobbs said. “I don’t know if it will come together, but sometimes you have to try.”